Give your simulator superpowers

RocketSim: An Essential Developer Tool
as recommended by Apple

Issue 280
Jul 15, 2025

This week's SwiftLee Weekly covers:

  • @Animatable in SwiftUI
  • Preparing for the future of App Development
  • 6 Mistakes that slow down development

Enjoy this week's SwiftLee Weekly!

THIS WEEK'S BLOG POST

​Modern Swift Lock: Mutex & the Synchronization Framework​

While actors work great in Swift Concurrency, they're not always the best choice. You might not want to introduce the overhead of async/await in some cases, in which a Mutex with Sendable support can be a way out.

SPONSORED

​Transform Your Career with the iOS Lead Essentials — Limited Offer​

Unlock over 40 hours of expert training, mentorship, and community support to secure your place among the best devs. Click now for early access to this limited offer and a FREE crash course!

CURATED FROM THE COMMUNITY

​Confirmation and Result Interactive Snippets​

Start with this post on interactive snippets and follow up with this week’s one. If your app has app intents, you want to build this in. If your app doesn’t have intents, you might want to consider intent-driven development.
​swiftjectivec.com​

​6 Mistakes That Slow Down Mobile Feature Development​

With AI tools at hand, it’s easier than ever just to get started coding. However, taking a step back to think things through is often wiser. And yes, you can use AI in that process, too!
​mobilesystemdesign.com​

​Introducing Animatable macro in SwiftUI​

The new @Animatable protocol in SwiftUI aims to make animations even more approachable.
​swiftwithmajid.com​

​Reaper - An open-source SDK for finding dead code​

After open-sourcing Launch Booster not long ago, we got another open-sourced framework. Even if you’re not looking to delete dead code, it’s going to be fun to look through the internals and see how this works!
​blog.sentry.io​

​What you need to know before migrating to Swift Testing​

I’ve migrated quite a few of my projects to Swift Testing already and found this article providing an excellent overview of things I found out the hard way. A must-read!
​soumyamahunt.medium.com​

​Four Months in the Making: SwiftMCP 1.0 is Here​

You might not all want to adopt the Model Context Protocol (MCP), but the way this project is set up is already worth a read. I love how they combine documentation and macros to integrate into existing projects more easily.
​cocoanetics.com​

SWIFT EVOLUTION

An overview of last week's Swift Proposal state changes. Check them out when they're in review, as it's your opportunity to influence the direction of Swift's future.

CODE SNIPPET OF THE WEEK

Mutex as a solution to non-sendable types

You can find this post on Twitter/X, LinkedIn, or Bluesky.

WHAT I'M WORKING ON

Preparing for the future of App Development

On a day-to-day basis I'm mostly working on my developer tool RocketSim. It's a project that started in 2019, so the code base starts to have places with outdated code.

I've been mostly working solely on this project, but invited two engineers to the team recently. This suddenly surfaced problems like outdated local packages and no CI integration for running all tests.

The latter is also a downside when you want to work with AI agents. They're great at opening PRs these days, but you want to validate the outcome by running your suite of tests.

In other words, I have to prepare my codebase for the future. I started a dedicated xcode-26 branch and dropped macOS 14 so I can fully adopt latest APIs. This included refactoring old CGWindow APIs to ScreenCaptureKit and migrating XCTest to Swift Testing.

These weeks are less fruitful feeling wise since I'm not doing many releases. Not having something tengible can feel demotivating—the opposite is actually releasing an app update with added value which always feels great. Yet, I do know what I'm working towards. Soon, I'll be able to easier invite other engineers or AI agents to the project and accelerate development due to having a modern codebase.

Sometimes, you have to take one step back to take two steps forward!

​

{% if subscriber.rh_reflink != blank %}EARN ROCKETSIM LIFETIME

Share and Earn RocketSim Lifetime & a 1-on-1 coaching session

Apple has recognized RocketSim as an Essential Developer Tool in the Mac App Store, and now you can get lifetime Pro access by sharing your unique referral link!
​​
How to get started:

​{{subscriber.rh_reflink}}
​​
Rewards:

  • Earn your first reward after just 3 sign-ups!
  • Check your progress anytime using your referral dashboard.
  • The grand prize? A personalized 1-on-1 career coaching session!

Several subscribers have already claimed their rewards—will you be next?{% endif %}

Thank you so much for your support, and until next Tuesday,

Antoine

Thanks for being a SwiftLee subscriber!
​
All my content is available to you for free. Like what I do and want to support me?
​Buy me a coffee or try RocketSim, an Essential Developer Tool as recommended by Apple.

This newsletter is built with Kit.
Need my experience? Book a 1:1 with me.

​